Methods of forming bodies of expandable foaming material

Details Methods of forming bodies of expandable foaming material Methods of forming bodies of expandable foaming material

1999-03-02

2001-08-07

Kuhns, Allan R. (Department: 1732)

Plastic and nonmetallic article shaping or treating: processes

Pore forming in situ

Composite article making

C264S046900, C264SDIG004

Reexamination Certificate

active

06270704

ABSTRACT:

FIELD OF THE INVENTION
The present invention is directed to methods of forming bodies of expandable foam material and a filter element seal formed by using that method and, more particularly, the present invention is directed to such a method and seal useful in configuring air filter elements.
BACKGROUND OF THE INVENTION
In air filters which are used for internal combustion engines, it is important to have substantially uniform air flow. This is because non-uniform air flow adversely affects the mass transfer function of the air stream, which decreases engine performance and raises exhaust emissions. In air filters, such as annular air filters, and more particularly, frustoconical air filters which are annular in cross-section, it has been found that reducing the height of a urethane seal adjacent the downstream clean side of the air filter improves air flow uniformity substantially. However, the prior art does not suggest just how this can be accomplished in an economical, feasible manufacturing process.
It is to be kept in mind that even a slight increase in engine performance and reduction in exhaust emissions is of considerable importance when that slight improvement is spread over an entire fleet of automotive vehicles. This is because that slight improvement, when combined with other slight improvements, eventually provides a substantial overall improvement which decreases fuel consumption of the fleet as well as harmful exhaust emissions of the fleet.
Generally, seals and gaskets formed on conical air filters are made of expanded urethane. It has been found that when attempting to lower the blow height of the urethane on the inside diameter of the filter media, sufficient flow or pressure from the foaming action is needed on the outside diameter of the filter media to form a blemish-free seal against a radial portion of a top mold. Moreover, since the outside diameter of the urethane flow is mechanically restricted and controlled, while the inside diameter is unrestricted, blow height is adversely impacted by the water content of polyol and the ratio of polyol to isocyanate, as well as other variables.
In an attempt to solve such difficulties, a number of methods were investigated which included manually restricting the blow on the inside, processing the urethane at different polyol to isocyanate ratios and different mold temperatures, and changing the chemistry of the urethane in order to reduce the blow. These methods failed due to either blemishes which formed on the outside diameter which forms the gasket for the filter element and/or high blow heights at the inside diameter of the filter element.
SUMMARY OF THE INVENTION
It is a feature of the invention to provide a new and improved method of forming bodies of expanded materials and of making and configuring seals for filter elements, wherein if the expanded materials are used for sealing air filters, air filters result which have improved air flow uniformity and thus an advantageous mass transfer function so as to enhance engine performance and reduce exhaust emissions.
In one aspect, the present invention is directed to a method for controlling the height differential in a mold utilizing a liquid starting material in which, as the liquid starting material solidifies into a solid body, it cures on a slanted mold face. By slanting the mold face from a first reference location to a second reference location which is beneath the first reference location, the liquid cures into a solid wherein the height of the volume of solid material is greater at the second reference location than at the first reference location.
In a further aspect of the invention, the liquid is a chemically or mechanically blown material such as urethane, plastisol, or silicone, which rises as it solidifies into a foamed solid volume which is higher at the second reference location than at the first reference location with respect to an imaginary horizontal plane through the solid body.
In a further aspect, the method is utilized for forming a seal for a pleated filter media having an upstream dirty side and a downstream clean side wherein the solid body forms a seal at an end of the filter media which is higher at the upstream dirty side than at the downstream clean side.
In still a further aspect of the invention, an annular filter element has at least one end sealed by a foam seal which extends to a greater axial height on the upstream dirty side than the downstream clean side.


REFERENCES:
patent: 4957672 (1990-09-01), Carter et al.
patent: 4975229 (1990-12-01), Kita et al.
patent: 5106397 (1992-04-01), Jaroszczyk et al.
patent: 5660771 (1997-08-01), Dunfee et al.

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